I don't believe the vampire "fetish" extends into gay circles. Oh, certainly, there are a few people that are into it. There are guys who are into gay guys in scuba gear or twinks that jackoff to balloons too, but it's not enough to build a niche around. Probably not even a single site.

Interestingly, AEBN offers a straight content feed that is vampire themed. And they also offer this amusing theater site...

Vampire Pay Per View

... with titles such as Ejactula, Vampire Call Girls, The Sexy Adventures of Van Helsing, Intercourse with a Vampire, and my personal favorite, Buffy the Vampire Layer.

--Aaron